Jump to content

Boiler Pressure Question

Rate this topic


John E

Recommended Posts

This morning, I noticed a steady drip coming out of my boiler's pressure relief valve. The pressure gauge was reading 35 pounds so I let a little pressure out manually through the valve until it was under 30, shut the boiler down, and replaced the pressure relief valve and the expansion tank.  Once the work was done, I turned the boiler back on and let it run through a few cycles. The pressure gauge was  reading 25. I just checked on it a few minutes ago and the pressure is back up to 35 but, nothing is coming from the pressure relief valve and I don't see any leaks. The new valve is a Watts.

 

Could the pressure gauge be off? If it was correct, shouldn't the relief valve be opening to let off PSI? Thinking I should replace it to verify what the pressure is.  

MEMBER: TEAM GREEN

SOL OG #47

Link to comment
Share on other sites

Posted (edited)

Update….

 

checked in it again.  There is water in the bucket under the pressure relief valve and psi is reading 35.  Dropped it down to 20. Water temp was 170.  Any idea as to why the pressure may be high.  Burnham gas boiler replaced after Sandy wiped out the previous one.  

Edited by John E

MEMBER: TEAM GREEN

SOL OG #47

Link to comment
Share on other sites

Do you have an automatic fill valve? 35 is high for a hot water with radiator system. 
 

Follow the supply pipe and see if there is a fill valve. If you find it you may be able to leave it closed. 
 

auto fill valves aren’t going to save your boiler. You are better off just checking the water level by eye every week or so. 

im sure there are differing opinions. 

 

No one expects the Spanish Inquisition.
Ce n'est pas le mur derrière lequel il se passe quelque chose, mais bien la cuisinière dans laquelle on a brûlé quelque chose

Link to comment
Share on other sites

My Burnham runs at between 17-20 psi. It's a 2 zone system. For me I know I will have a higher pressure if I have air in the lines. Maybe a good bleeding will bring your pressure down. 

 

There should be a pressure reducing valve that only allows incoming water from a well or city supply to enter the boiler at a set low pressure. Water pressure straight from a well pump or city supply is typically way too high for boiler and could cause damage. You know the max pressure of the boiler is 35psi because the pop off you replaced is a 35 pounder.  You need the low pressure water supply to the boiler open so that the boiler is constantly replenished and kept full, even after "filling a bucket" from the pop off or during bleeding. Dry boiler is bad. Air in system bad.

 

IMO if the gauge is reading 35psi and the needle is moving down when you pull the pop off so it sounds like the gauge is working. 

 

I would try bleeding first since it's the cheapest solution. I bleed mine into buckets so that I can watch for bubbles.

 

I have had less issues with air after installing a couple of automatic air bleed vent.

Fishing is a delusion entirely surrounded by liars in old clothes.
Link to comment
Share on other sites

The new expansion tank may have lost its pre- charge, tank pressure should match system pressure. Adjust the auto feed or choke down the valves next to it to see if the pressure stays normal. I wouldn’t use the relief valve to vent water and pressure, it will weaken and eventually drip.

Tis better to remain silent and thought the fool, than to speak and remove all doubt.

Link to comment
Share on other sites

Is there a tankless coil for domestic HW?
  You may have to drain your heating loops and refill the system to get the pressure normal. Purge the air out into a bucket while filling the loops to check for air/bubbles.

Tis better to remain silent and thought the fool, than to speak and remove all doubt.

Link to comment
Share on other sites

9 hours ago, jmlandru said:

Do you have an automatic fill valve? 35 is high for a hot water with radiator system. 
 

Follow the supply pipe and see if there is a fill valve. If you find it you may be able to leave it closed. 
 

auto fill valves aren’t going to save your boiler. You are better off just checking the water level by eye every week or so. 

im sure there are differing opinions. 

 

Doesn't work in a hydronic system, it's just supposed to be full, no sight glass. I have a steam system with a VXT autofill that's not working. Very annoying as I do not live there. 

Edited by gellfex
Link to comment
Share on other sites

This morning, there was a little water in the bucket and pressure was hair under 30 (too high but less than 35 I was getting last night). I was able to bleed some air out of the system but, there is still more in there. Left the system with 18 psi. I will bleed it again when I get home from work and have more time to play with it.

 

It is a hydronic hot water system (Burnham boiler) with a large indirect hot water tank set up as one of the zones. 5 zones total. I double checked the shut off valves for the autofill.  The valves are currently open except for the bypass valve which allows water into the system directly from the domestic water feed.

MEMBER: TEAM GREEN

SOL OG #47

Link to comment
Share on other sites

Posted (edited)

Been playing with this a little more and had a boiler guy come in for a look.  Seems  to be the water pressure reduction valve based in what I’ve seen by closing feed lines.  It holds steady when disconnected from the feeder but creep up when the feed is opened. 
 

Boilerer guy said it could be backfeeding into the boiler loop through the indirect hot water heater.  It’s not that old but who knows.  

 

Edited by John E

MEMBER: TEAM GREEN

SOL OG #47

Link to comment
Share on other sites

You need to check the pressure after the auto feed, should be 10-25 or so. They are adjustable! A new one is $90

15 hours ago, John E said:

 

Boilerer guy said it could be backfeeding into the boiler loop through the indirect hot water heater.  It’s not that old but who knows.  

 

If this is true you are a check valve away from success.

Edited by cheech
Spell

Tis better to remain silent and thought the fool, than to speak and remove all doubt.

Link to comment
Share on other sites

On 4/16/2024 at 9:55 PM, John E said:

Been playing with this a little more and had a boiler guy come in for a look.  Seems  to be the water pressure reduction valve based in what I’ve seen by closing feed lines.  It holds steady when disconnected from the feeder but creep up when the feed is opened. 
 

Boilerer guy said it could be backfeeding into the boiler loop through the indirect hot water heater.  It’s not that old but who knows.  

 

Shutting off the water inlet and holding a steady pressure proves it’s not the indirect tank. Replace the water inlet regulator.

Link to comment
Share on other sites

The saga continues...

 

By shutting the valves feeding the boiler system (through pressure reduction valve and bypass), I was able to get the boiler to maintain a steady pressure of 30 psi. The pressure release valve went off once or twice in between the times I was checking it as there was a small amount of water in the bucket.  So, I replaced the water pressure reduction valve and the shut off valve in the bypass loop around the reduction valve (it was old and I was thinking why not if I can take another possibility out of the equation). That was Thursday night. Since then, no water out of the pressure release valve and the boiler pressure has been reading a steady 30 psi. I have tried to let some water out of the boiler to take the pressure down and got the air out of the system. When I opened the drain, the pressure went below 20 but it went right back to 30 next time the boiler ran.

 

My next step is to get a pressure gauge that I can screw onto the drain to double check the reading on the tridicator gauge. Perhaps the tridictator is off? At this point, I don't think it an issue with the indirect tank.  I'd hate to send the $$$ to replace it only to find out it was something else.

MEMBER: TEAM GREEN

SOL OG #47

Link to comment
Share on other sites

Pretty sure for a 2 story house you only need to run 12-15 lbs boiler pressure. 
30 psig is to close to relief valve rating and it will bleed off as water heats and expands.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to register here in order to participate.

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×
×
  • Create New...